Serotonin (5-hydroxytryptamine; 5-HT) mediates many central and nervous system functions by its interaction with specific neuronal receptors. It is well established that 5-HT receptors are related to anxiety and mental depression. 5-HT receptors are also binding sites for hallucinogenic drugs. Physiological functions such as blood vessel contraction and platelet shapes are also regulated by 5-HT receptors. Physiological, pharmacological, and molecular cloning studies have identified thirteen serotonin receptors belonging to seven subtypes. The molecular cloning of serotonin receptors provides a great understanding of the structure and function of these pharmacologically important receptors. The 5-HT2 receptors may be considered as a protoype for the study of serotonin receptors. A better understanding of the localization and regulation of 5- HT receptors may lead to development of receptor specific drugs. MAbs are not available to different 5-HT receptor subtypes. Using synthetic peptides and recombinant proteins as immunogens monoclonal antibodies will be made to 5-HT2 receptor subtypes. Antibodies will be screened for their utility in immunohistochemistry, western blot, and immunoprecipitation. Monoclonal antibodies to the 5-HT2 receptors can serve as a valuable adjunct to classical radioligand binding for immunolocalization and regulation studies. PROPOSED COMMERCIAL APPLICATION: At present, MAbs against 5-HT receptors are not available. The approaches used in the Phase study to develop mAbs against 5-HT2 receptors will be used to generate mAbs against other 5-HT receptor subtypes in Phase 11. The results of these studies should provide tools which can readily be commercialized as research reagents. Since, these mAbs will be used by both research scientists and clinical pathologists, the market is of a reasonable size.